Wrestplanks



May 28, 1963 F. H. WALSH 3,091,149

WRESTPLANKS Filed Nov. 20, 1959 Zig. 4. Z5'

INVENTOR /'J ATTORNEY United States Patent() 3,091,149 WRESTPLANKS FrankH. Walsh, West Hempstead, N.Y., assgnor to Steinway & Sons, Long IslandCity, N .Y., a corporation of New York Filed Nov. 20, 1959, Ser. No.854,375 2 Claims. (Cl. 84-209) The present invention relates to pinblocks or wrestplanks for tuning pins in pianos and like musicalinstruments.

An important object of the invention is to provide a multilayerwrestplank which is capable of more securely holding a series of tuningpins regardless of the direction of the stresses to which the pins aresubjected by the piano strings, in which the grain of at least one layeris always exactly or nearly parallel with the direction of maximumstress upon the pin, in which a greater percentage of end grain bearingis located in the plane of maximum stress on the pin, and which isequally advantageous for both grand pianos and uprights.

Another object of the invention is to provide a wrestplank of the aboveoutlined characteristics which is of a balanced construction, Whoseretaining action upon the pins is less dependent upon the moisturecontent of the surrounding air, and which remains dimensionally morestable under all conditions.

An additional object of the instant invention is to provide a wrestplankfor tuning pins in upright pianos, grand pianos and -like musicalinstruments which is so constructed as to eliminate the so-calledstick-slip phenomenon in that its retaining action upon the tuning pinsis more nearly uniform in all directions than in the Wrestplanks ofpresently known construction, and which will provide a better hold onthe tuning pin, in that the latter is held tighter in a hole of the samesize as before yet turns more smoothly and easily, and sets in desiredsetting easily, exactly and firmly, thus affording easy yet solid tuningand maintaining these qualities throughout long periods of use.

A concomitant object of the invention is to provide a multilayerwrestplank in which the direction of grain in the various layers orplies is uniformly and symmetrically distributed in the radialdirections of each tuning pin, and which requires a lesser number oflong-grain plies.

It has been found by extensive experimentation that the deformation ofholes or bores in which the tuning pins are held in a wrestplank isgreatly reduced if the direction of grain is parallel with the directionof stresses to which the pins are subjected by the piano strings. Inother words, it is desirable that at least some end grain yshould bearagainst that side of each tuning pin which exerts pressure against thematerial of the wrestplank. The term end grain is intended to describethe exposed fibers cut transversely to the grain, i.e. endwood, Theruptured fibers of the endwood are believed to be primarily responsiblefor proper retention of the tuning pin. Thus, a satisfactory retentionof a tuning pin is insured if the wrestplank is constructed in such away as to have more end grain bearing on each pin in the location ofmaximum stress, namely, in the direction of the pull of the string.However, since the stress is applied to the pins at varying anglesthroughout the piano, the end grain, too, must be arranged at varyingangles. For example, in treble strings, the strings usually lie at rightangles to the longitudinal direction of the wrestplank, the bass stringsmay enclose an angle of as little as 55 degrees with the longitudinaldirection of the wrestplank, and in the center section the angle isoften about 65 degrees.

The advantageous retaining action of endwood or end y ICC grain appearsto be due largely to the fact that endwood is dimensionally stable sincewood does not tend to expand or contract along the grain but ratheracross the grain. Data recently compiled by the Forest ProductsLaboratory, an agency of the U.S. Department of Agriculture, indicatethat the compressive strength of hard maple, a material most frequentlyutilized in the manufacture of wrestplanks, as regards endwood is atleast three times greater than as regards side grain, and that theelasticity, too, is ten to twenty times greater. Thus, if the wrestplankoffers endwood in the direction of maximum stresses to which it issubjected by the tuning pins, the likelihood of deformation of thetuning pin hole is much smaller than if the stresses would act acrossthe grain, i.e. in a direction at right angles to the grain. Bypresenting more endwood bearing to the pin in the plane of the greatestload on the pin, a stronger hole wall is provided and the hole willv notlose its shape or fit under load as much as in presently knownconstructions. In addition, such wrestplanks offer more elastic bearingfor the pin in their plane, this being the important quality whichinsures that the pin is held tight and remains tight over many years ofuse.

As is known, an improperly constructed wrestplank cannot prevent thatthe hole is deformed from a circular to a slightly oval or egg-shapedform, this being due to improper, non-uniform distribution of endwoodaround the hole, i.e. to such arrangement of grain that a smallerproportion of endwood is present in line of the maximum pull exertedupon the pin 4by a piano string. Thus, it is desirable toy eliminateside grain bearing on the pin in the maximum stress location since, asmentioned hereinbefore, the compressive strength and elasticity of Woodin a direction parallel with the grain is several times ygreater thanacross the grain. In addition, side grain on the exposed edge of alamination in the wrestplank is subject to comparatively greaterswelling and shrinking, which also tends to distort the hole. Withrepeated cycles of swelling and shrinking, the wood will take acompression set and will actually compress the fibers which results infurther deformation of the hole out of the round.

The tuning p-ins in wrestplanks for pianos and like musical instrumentsare generally drive-fit, their diameter being normally .281, and thepins are driven into holes or bores of smaller diameter, e.g. .253" orthereabouts.

In accordance with the present invention, the wrestplank preferablycomprises lfour central or Working layers or plies of preferably uniformthicknesses, and the layers are arranged in such a way that at least onethereof yoifers end grain bearing to each vtuning pin in line of maximumstress on the pin. When the wrestplank cornprises four working plies,the angle enclosed by the grain of two outer working plies with thegrain orf the adjacent median Working plies is less than degrees, andpreferably 45 degrees since this alignment is not only symmetrical `andbalanced but gives maximum contrast of grain direction of adjacent pliesand thus maximum stabili- 4ty. It can be said that the grain in theplies assumes a star shape and, consequently, each tuning pin driveninto a hole formed in a so constructed wrestplank will `always bearagainst the end grain of at least one layer regardless of the directionin which the pin is pulled by the respective string. In addition, andsince the arrangement of grain in the layers constituting the workingplies of the improved wrestplank is preferably symmetrical,substantially equal areas of end grain will bear against each pin, whichinsures that all pins are held with substantially equal force in anygiven position selected by the tuner regardless of the direction inwhich a pnl-l is exerted by the piano strings.

Another advantage of arranging the plies or lamina- 3 tions in suchmanner that the grain in adjacent plies crosses at `angles of less than9()` degrees, and preferably at 45* degrees, is in that shorter cuttingsof material may be used. This is a distinct advantage in the manufactureof wrestplanks since the wood most frequently utilized therefor iscarefully selected, iiawless, quarter-sawn hard maple which is difficultto obtain, especially in longer lengths.

The invention will be described in greater detail with reference to theaccompanying drawing, in which:

FIG. l is end elevational View of one embodiment of my invention,showing a wrestplank which is particularly suitable for use in uprightpianos, with the layers or plies partly broken away to reveal a bore forthe tuning P111;

FIG. 2 is a smaller-scale top plan view 0f the structure shown in FIG. lwith the layers broken away in stepwise fashion and with double arrowsindicating the direction of grain in the layers;

FIG. 3 illustrates, in a view similar to that of FIG. l, a slightlydifferent wrestplank for use in grand pianos; and

FIG. 4 is a diagrammatic view illustrating the position of a tuning pinwith respect to the direction of grain in the improved wrestplank.

Referring now in greater detail to the drawing, and first to FIG. 1, thewrestplank or pin block 1i) therein shown comprises six plies orlaminations made of a suitable wood, preferably a carefully selected,flawless, quarter-sawn hard maple or an equivalent hard wood. The fourcentral or working plies 11, 12, 13 and 14 are of equal thicknesses andare received between a top veneer 15 and a solid hard wood lill piece orbottom layer 16. The thickness of the top veneer 15 is less than thethickness of the fill piece or bottom layer 16. Such wrestplank isparticularly suitable for use in upright pianos. By way of example, thethickness of the individual working plies 11 to 14 may be about 5/16,the thickness of the top layer or veneer 15 is then about 1/s, and thethickness of the fill piece or bottom layer 16 is about 1/2 The tuningpin 17 4is shown as driven into a hole or bore 18 formed at one end ofthe wrestplank 10 in the 'bass section. As is illustrated in FIG. 2, thestring 19 encloses lan angle of about 55 degrees with the long-itudinaldirection of the Wrestplank 10. A schematically indicated second string19 which is connected to a pin in the central section `of the wrestplankenoloses with the latters longitudinal direction an angle of about 65degrees, and a third schematically shown string 19" in the treblesection extends at right angles from the member 10. The pin 17 bearswith the greatest force against that portion of the Wall of bore 18which is in line with the longitudinal direction of the string 19.

The direction of grain in the individual plies or layers is also shownin FIG. 2. The members 15, 16 are long grain, i.e. their grain runs inthe longitudinal direction of the wfrestplank 10 parallel with the edge10a, as is indicated by the double arrows 20, 21, respectively. Thewrestplank tapers from the bass section toward the treble section (seethe inclined longitudinal edge lib). The grain 'of the central orworking plies 11 to 14 is indicated by the double arrows 22 to 25 inthat order. The outermost working plies 11, 14 are cross grain in thewrestplank, and the grain of the two median working plies 12, 13 isinclined through 45 degrees with respect to the grain in the plies 11,14, respectively. Thus, the working layer 13 (see the double arrow 24)presents endwood as a `bearing to the pull on the tuning pin 17, Whilethe layer 12 (see the double arrow 23) presents endwood bearing to thepull on the pin connected to the string 19. The pin connected to thestring 19" in the treble string section bears against the endwood oflaminations 11 and 14 in the line of pull (see the double arrows 22,25).

The wrestp-lank 110 'of FIG. 3 is preferred for use in grand pianos. Thecentral or working plies 111 to 114 are of equal thicknesses, and thethickness of the top layer or veneer 115 equals the thickness of thebottom layer or veneer 116. By Way of example, the thickness of eachworking ply may be in the range of about 5/16", and the thickness of theveneers 115, 116 may be in the range of about 1/s. The direction ofgrain in the plies 111 to 114 and in the layers 115, 116 is identicalwith that indicated by the arrows 251 to 25 in FIG. 2.

The arrangement of grain with respect to the tuning pin 17 isillustrated somewhat schematically in FIG. 4 which shows only thedirection of grain with the plies 11 to 16 or 111 to 116 omitted. Itwill be noted that the layers are arranged in such a Way that theirgrain directions run radially with respect to the pin axis; thus, thelatter bears at locations of maximum stress against the ruptured endwoodfibers of at least one working lamination (double arrows 22 Ito 25)regardless of the direction in which the pin is pulled by the pianostring. As mentioned hereinbefore, the string 19 subjects the pin 17 tomaximum stress in a direction substantially parallel with the doublearrow 24 (layer 13 or 113).

The novel wrestplank features a more uniform distribution of end grainbearing or endwood on each tuning pin and, in fact, the endwoodvirtually surrounds the pin, as is best shown in FIG. 4. Equal thicknessof the working plies 11 -to 14 or 111 to 114 also contributes to betterdistribution of stresses, and the tendency to warp or otherwise deforrnis less pronounced. This results in a more balanced and thus more stablewrestplank.

The disposition of the central plies 12, 13 or 112, 113 lat an `angle of45 degrees to the main axis of the wrestplank distributes the internalstresses in a more uniform Way. Such stresses arise upon expansion andcontraction of the wood under varying conditions of moisture content dueto changes in the atmosphere. The uniform distribution of internalstresses results in a more stable construction which, of course, is amajor requirement to be met by the wrestplank.

It is well known that wood, even when seasoned, remains hygroscopic andtends to give up moisture to dry air or absorbs moisture from the moistair to either shrink when drying or to expand when becoming Wetter. Suchdimensional variations are negligible along the grain but areconsiderable across the grain; therefore, a plied construction vvithalternating grain directions remains. comparatively stable because theadhesive bond between the plies will tend to prevent or at least toreduce the dimensional changes in the piece by locking the expandingplies to the non-expanding plies. It is preferred to arrange the pliessymmetrically and touse working plies of equal thicknesses, of the samekind of wood `and grain figure in order to equalize the stresses and tothus balance the wrestplank, which will accordingly remain stable.

By using a Wrestplank in which the grain of the median work-ing plies12, 13y and 112, 113, respectively, is inclined with respect to thegrain of the outer working plies 11, 14- and 111, 114, respectively,through iess than degrees and preferably through an angle of 45 degrees,the stresses .are distributed more evenly which results in more uniformand better balanced Wrestplank under varied climatic conditions.

The timing pins driven into the holes formed in a wrestplank constructedin accordance with the present invention will remain tight and willpreserve their tightness for long periods of time. As above mentioned,the plies of a wrestplank, [like any Wood, tend to shrink in dry air andto expand in moist air. When a wrestplank is exposed to dry air,:shrinkage will cause side grain exposed to the tuning pin to shrinkaway from the tuning pin and reduce the overall area of the bearingsurface for the pin. Swelling will cause side grain exposed to the pinto `bind unduly on the pin and, eventually, through compression set, toreduce the bearing area or tightness still further when the wood vagaindries and shrinks. The hole tends to become oval. As shown in FIG. 2,the

novel construction in which the grain in the working plies is arrangedat various angles, 4i.e. also in the directions other than=longitudinally and transversely of the Wrestplank, the detrimentaleffects of swelling and shrinkage are reduced or completely eliminated.This is due to the fact that more end grain and hence a dimensionallymore stable bearing surface Vsurrounds the tuning pin in substantiallyall directions. Such grain alignment in the working plies results inbetter dimensional stability and in a stronger, tougher and more elastic4bearing for the tuning pin under load.

It has also been found that the improved wrestplank brings about Ianimproved performance of 4the tuning pins as there is very littlevariation between the initial torque necessary to start the turningmovement of a tuning pin lin its seat and the moving ltorque necessaryto move the pin in its seat. It may be mentioned here that thedifference between the initial and moving torque is considerable -inpresently utilized wrestplanks. Moreover, the so-called stick-slipphenomenon, undesirable and often causing considerable problems in thewrestplanks of prior construction, is eliminated by the arrangement ofworking plies in accordance with the present invention. Thecharacteristic of the stick-slip is that the tuning pins turn unevenly,at times freely and at times sticking to such an extent as to requireconsiderably increased force to continue the turning of the pin. Suchpins are called creaky `or jumpy by expert piano technici-ans and arediicult to set, or locate precisely and solidly in angular positionsince small precise movements of the tuning pin are necessary to put thepiano string in exact tune. In the novel wrestplank, the tuning pin canbe turned smoothly and will hold tight in any desired angular position.There is a better hold of the tuning pins in the wrestplank, the pinsare tighter in a hole of the same size as before and, since theelasticity of the wrestplank is preserved, it is not necessary to use alarger hole.

Tuning `in the improved wrestplank is not only easy but results in good,solid tuning. Despite the high torque or tightness of the tuning pin inits hole, lthe pin will move smoothly without creak or jump, and willset firmly at any desired point. The rastio of initial torque or forcenecessary to move the pin from its seat to the moving torque or forcenecessary to keep the pin turning is either equal or very close, in theorder of 160 to 150 or more inch pounds. At lower torques, the ratio issubstantially oneJto-one; in other words, the forces are equal. This isa considerable advantage over previous practices in ease and accuracy oftuning.

ilt has been found that' Ithe above enumerated advantages of theimproved wrestpliank remain unchanged for long periods Iof time. By thetime the piano has its third tuning, 70 to 80 percent of the lirmness ortorque remains inthe pins. At the end of six months or a year, thefirmness or torque no longer drops but remains at a very satisfactorylevel of up to percent of the original torque. Thus, the drop intightness is low yas compared with that in wrestplanks of presentlyutilized construction. Torque will drop from about 150 inch pounds toapproximately inch pounds, whereas a drop to 80 inch pounds is typicalof fthe presently utilized constructions. Moreover, the advantageouscharacteristics` of .tight-ness, smoothness, equality of initial andmoving torque, and lack of creakiness, too, remain unchanged.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt i-t for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What I claim and desire to protect by Letters lPatent 1s:

1. A Wrestplank for use in a stringed instrument comprising a firstouter working ply, a second outer working ply, and -two median workingplies, a tuning pin extending through said plies, the grain of saidouter working plies being parallel with respect to the transversedimension of the wrestplank, the grain of said median working pliesbeing substantially perpendicular to each other and enclosing angles ofabout 45 with the grain of said first and second outer Working pliesrespectively, whereby said tuning pin is substantially surrounded by andin engagement with end wood.

2. A wrestplank for use .in a stringed instrument comprising at leastfour working plies of quarter-sawn lumber, a tuning pin extendingthrough said plies, said working plies including `a first outer workingply, a second outer Working ply and two median Working plies, the grainof said outer Working plies being parallel with the transverse dimensionfof the wrestplank and the grain of said median Working plies beingsubstantially perpendicullar lto each other and enclosing angles ofabout 45 with the grain .of said first land second outer working pliesrespectively, whereby said tuning pin is substantially surrounded by-and in engagement with end wood.

References Cited in the le of this patent UNITED STATES PATENTS 368,673Keller Aug. 23, 1887 2,101,920 Schroeder Dec. 14, 1937 2,151,505Elmendorf Mar. 2l, 1939 2,578,781 Brundige Dec. 18, 1951

1. A WRESTPLANK FOR USE IN A STRINGED INSTRUMENT COMPRISING A FIRSTOUTER WORKING PLY, A SECOND OUTER WORKING PLY, AND TWO MEDIAN WORKINGPLIES, A TUNING PIN EXTENDING THROUGH SAID PLIES, THE GRAIN OF SAIDOUTER WORKING PLIES BEING PARALLEL WITH RESPECT TO THE TRANSVERSEDIMENSION OF THE WRESTPLANK, THE GRAIN OF SAID MEDIAN WORKING PLIESBEING SUBSTANTIALLY PERPENDICULAR TO EACH OTHER AND ENCLOSING ANGLES OFABOUT 45* WITH THE GRAIN OF SAID FIRST AND SECOND OUTER WORKING PLIESRESPECTIVELY, WHEREBY SAID TUNING PIN IS SUBSTANTIALLY SURROUNDED BY ANDIN ENGAGEMENT WITH END WOOD.